悬浮液进样石墨炉原子吸收光谱法测定地质样品中痕量镓和铊

对固体悬浮液直接进样及石墨炉原子吸收光谱法测定Ｇａ和Ｔｌ进行了研究，拟定了以琼脂为悬浮剂，Ｎｉ（对Ｇａ）和Ｖ（对Ｔｌ）为基体改进剂，标准溶液进行校准的、灵敏、快速、准确测定Ｇａ和Ｔｌ的方法。在选定条件下，测得Ｇａ和Ｔｌ的特征量（１％吸收）分别为２．８×１０￣（－１１）ｇ和４．４×１０￣（－１１）ｇ，检出限（３σ）分别为２４ｐｇ和２８ｐｇ，相对标准偏差分别为６．３％（含Ｇａ６．４ｇ／ｇ，ｎ＝１１）和４．８％（含Ｔｌ１．０ｇ／ｇ，ｎ＝１３）。方法适用于地质样品中低至０．１ｇ／ｇＧａ和Ｔｌ的测定。     

石墨炉蒸发硫化铝双原子分子吸收光谱法测定硫

介绍了以空心阴极灯代替连续光源，确定了硫化铝双原子分子吸收光谱法测硫的最佳条件，方法的灵敏度（０．００４４Ａ）为３×１０￣（－９）ｇＳ，测定含Ｓ１０ｇ／ｍｌ试样１０次，其ＲＳＤ为３．３％，标准加入回收率在９９％～１０４％之间。用所拟方法测定了大气硫酸盐化速率，结果与比色法符合。     

双最大吸收波长光度法测定天然水中的银

在乙酸介质中,银(Ag~+)亚铁氰化钾—邻菲啰啉反应有催化作用,体系由红色渐变为蓝绿色。据此,本文依据稳定悬浮体系光学吸收性质、研究双最大吸收波长以测定银的新方法。该方法将红色褪色和绿色生色双定量联系起来,分析灵敏度比单波长法提高1倍,而且操作较简单,精密度较高,计算曲线稳定,适合于天然水和部分较洁净污水中Ag的分析。     

内蒙古白乃庙金矿床石英脉中绢云母可见光光谱特征及其地质意义

以简单、经济的可见光吸收光谱方法研究了绢云母可见光光谱特征,结果表明含矿石英脉中绢云母可见光光谱在650~700nm之间透射率高,并总结了透射率与Fe含量和寄主脉金品位之间的关系。·     

微波炉消解原子吸收法测定铜精矿中多元素

研究了用微波炉消解铜精矿,原子吸收光谱测定其中As、Pb、Zn、As、Sb和Hg的方法。讨论了消解体系的选择和微波炉消解程序。样品经HNO_3-HCl一次消解便可连续测定6个元素,方法简便快速,与国标方法进行了比较,结果一致。     

石墨炉原子吸收光谱法测定地质样品中的痕量铂、钯

本文提出了用717阴离子交换树脂富集铂、钯的石墨炉原子吸收光谱分析方法。对富集铂、钯的条件,共存离子的干扰情况以及在GF-2000型石墨炉中测定铂、钯的最佳条件进行了研究。样品用王水分解后,在10％的王水介质中,用717阴离子交换树脂富集铂、钯,以热的硫脲溶液解脱,在拟定的工作条件下,于石墨炉原子吸收光谱仪上进行测定,大量的共存离子不干扰测定。方法简便快速,检出限分别为Pt8.8×10~(-9)g/ml,Pd3.4×10~(-9)g/ml,方法的相对标准偏差分别为Pt7.09％Pd11.48％,适用于地质样品中铂、钯的测定,结果令人满意。     

Multifunctional vibration–absorption RC megaframe structures and their seismic responses

The multifunctional vibration–absorption RC megaframe structures, which act as tuned mass dampers, base isolators and damping energy‐dissipaters, are presented. The proposed systems are essentially different from the normal megaframe structures in earthquake responses, failure mechanism, and theoretical model of seismic design. The elasto‐plastic dynamic analyses show that the earthquake responses of the multifunctional vibration–absorption RC megaframe structures decrease significantly in comparison with the normal megaframe structures, namely 60–80 per cent decrease of the earthquake responses of the major frames and 70–90 per cent decrease of the ones of the minor frames. Copyright © 2000 John Wiley & Sons, Ltd.     

Mixing metals in the early Universe

We investigate the evolution of the metallicity of the intergalactic medium (IGM) with particular emphasis on its spatial distribution. We propose that metal enrichment occurs as a two-step process. First, supernova (SN) explosions eject metals into relatively small regions confined to the surroundings of star-forming galaxies. From a comprehensive treatment of blowout we show that SN by themselves fail by more than one order of magnitude to distribute the products of stellar nucleosynthesis over volumes large enough to pollute the whole IGM to the metallicity levels observed. Thus, an additional (but as yet unknown) physical mechanism must be invoked to mix the metals on scales comparable to the mean distance between the galaxies that are most efficient pollutants. From this simple hypothesis we derive a number of testable predictions for the evolution of the IGM metallicity. Specifically, we find that: (i) the fraction of metals ejected over the star-formation history of the Universe is about 50 per cent at     that is, approximately half of the metals today are found in the IGM; (ii) if the ejected metals were homogeneously mixed with the baryons in the Universe, the average IGM metallicity would be     at     However, due to spatial inhomogeneities, the mean of the distribution of metallicities in the diffusive zones has a wide (more than 2 orders of magnitude) spread around this value; (iii) if metals become more uniformly distributed at     as assumed, at     the metallicity of the IGM is narrowly confined within the range     Finally, we point out that our results can account for the observed metal content of the intracluster medium.     

A wavelet analysis of the spectra of quasi-stellar objects

The temperature of the intergalactic medium (IGM) is an important factor in determining the linewidths of the absorption lines in the Ly α forest. We present a method to characterize the linewidth distribution using a decomposition of an Ly α spectrum in terms of discrete wavelets. Such wavelets form an orthogonal basis, so the decomposition is unique. We demonstrate using hydrodynamic simulations that the mean and dispersion of the wavelet amplitudes are strongly correlated with both the temperature of the absorbing gas and its dependence on the gas density. Since wavelets are also localized in space, we are able to analyse the temperature distribution as a function of position along the spectrum. We illustrate how this method could be used to identify fluctuations in the IGM temperature that might result from late reionization or local effects.     

Selective Preconcentration of Trace Amounts of Cu(II) With Surface‐Imprinted Multiwalled Carbon Nanotubes

In this study, a new sorbent is synthesized using surface imprinting technique. Cu(II)‐imprinted multiwalled carbon nanotube sorbent (Cu(II)‐IMWCNT) is used as the solid phase in the solid‐phase extraction method. After the preconcentration procedure, Cu(II) ions are determined by high‐resolution continuum source atomic absorption spectrometry. A total of 0.1 mol L^?1 ethylenediaminetetraacetic acid (EDTA) is used to remove Cu(II) ions from the sorbent surface. The optimum experimental conditions for effective preconcentration of Cu(II), parameters such as pH, eluent type and concentration, flow rate, sample volume, sorbent capacity, and selectivity are investigated. The synthesized solid phase is characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The maximum adsorption capacities of Cu(II)‐IMWCNT and non‐imprinted solid phases are 270.3 and 14.3 mg g^?1 at pH 5, respectively. Under optimum experimental conditions for Cu(II) ions, the limit of detection is 0.07 μg L^?1 and preconcentration factor is 40. In addition, it is determined to be reusable without significant decrease in recovery values up to 100 adsorption–desorption cycles. Cu(II)‐IMWCNT have a high stability. To check the accuracy of the developed method, certified reference materials, and water samples are analyzed with satisfactory analytical results.